He has an army of fans and is coming to a cinema near you soon. The SpongeBob SquarePants Movie opens in the US on Friday. But who is SpongeBob, and why is he so popular?

Always happy: SpongeBob SquarePants

SpongeBob lives in a pineapple at the bottle of the sea. A bright yellow sponge, he always wears a boy scout's outfit, and always has a buck-toothed grin on his face. He works in Krusty Krab restaurant, cooking Krabbie Patties. He enjoys catching jellyfish and spending time with his best friend, Patrick, a starfish.

How did it all start?
SpongeBob SquarePants made its debut in 1999 on children's channel Nickleodeon, and quickly became one of the channel's most popular programmes. It is aimed at under-11s, but has built up a cult following among adults - with evening repeats on music station MTV.

Creator Stephen Hillenburg pitched the idea to Nickleodeon while working as an animator on another series, Rocko's Modern Life.
SpongeBob's theme song runs: "Who lives in a pineapple under the sea? SpongeBob SquarePants! Absorbent and yellow and porous is he. SpongeBob SquarePants!"

Hasselhoff and Johansson meet Patrick and SpongeBob

Who are SpongeBob's friends? The community of Bikini Bottom contains a wide range of characters. Patrick Star, a plump, gullible starfish, is SpongeBob's closest friend. Sandy Cheeks - a sports-loving squirrel who lives in a tree dome and wears an air-filled suit - is another pal. SpongeBob's boss is the money-loving Mr Krabs, while his neighbour, the eternally pessimistic Squidward Tentacles, works alongside him in the Krusty Krab. SpongeBob has a pet snail, Gary, who is super-smart and meows like a cat.

Who are SpongeBob's enemies? SpongeBob is loved by everybody, but the show does have one bad guy - Bubble Bass. Plankton, the owner of the rival Chum Bucket restaurant, is always trying to steal the recipe for the Krabby Patty burger from the Krusty Krab - but always fails.

Is there a special somebody in SpongeBob's life? SpongeBob's sexuality has been a hot topic ever since the show built up its adult following.

In 2002, Stephen Hillenburg denied his character - who holds hands with Patrick and attends Mrs Puff's boating school - was gay. He said he saw SpongeBob as being "asexual". He added: "Everybody is different and the show embraces that. SpongeBob is an oddball. He's kind of weird, but he's kind of special."

Avril Lavigne is on the SpongeBob soundtrack

Who are SpongeBob's fans? Earlier this year, more than 700 fans set up the Church of SpongeBob, which meets for services in New York, Texas and California.

The church's manifesto says it wants to push "simple things like having fun and using your imagination", and offers study courses on the cartoon.

Cult band the Flaming Lips feature on the soundtrack, with the single SpongeBob & Patrick Confront the Psychic Wall of Energy.The video features singer Wayne Coyne and bandmates dressed as different pieces of food, in a giant, salivating mouth.The soundtrack also features a version of the theme tune by Avril Lavigne.

Wayne Coyne's Flaming Lips are also on the soundtrack

What is the film like? The film sees SpongeBob and Patrick leave Bikini Bottom to search for King Neptune's stolen crown. It also features a live-action cameo from Baywatch star David Hasselhoff, who befriends the pair as they try to save Bikini Bottom from destruction.

Work on the TV show was halted so the team behind the film could work on the movie. Its release coincides with the Thanksgiving holiday in the US, although SpongeBob's movie debut has been a little overshadowed by Pixar's The Incredibles, which was released two weeks ago.

When can I see it in the UK? The SpongeBob SquarePants Movie is due to get its UK release on 11 February. On TV, it shows at 1530 on weekdays and daily at 2100 on Nickleodeon, with extra screenings on Nicktoons TV and Nick Replay.